JP2568839B2 - High durability sound absorbing insulation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a muffler for exhaust noise of an automobile engine.

[Prior art and its problems] Conventionally, a muffler for exhaust sound of an automobile engine is made of an inner pipe through which exhaust gas passes and a metal container covering the inner pipe.

However, in recent years, regulations on noise have become more stringent, and the temperature of exhaust gas has also been increasing due to higher performance of engines and more efficient exhaust gas catalysts.

As a countermeasure, the shape inside the metal container has been complicated and the metal container itself has been increased in size. A muffler that supports a sound absorbing material such as glass worm with a punching metal or the like has been used on the inner peripheral wall of a metal container.

In order to further improve the sound absorbing effect, a muffler called a pre-muffler has been used in an exhaust pipe system between the engine and the conventional muffler.

However, in the pre-muffler using the glass wool for the inner peripheral wall, the heat resistance temperature of the glass wool is as low as 500 ° C. due to its composition. Shrinkage occurs, and the fibers of the fiber are powdered by the vibration of the vehicle, and the fibers are scattered by the exhaust gas flow, which causes the sound absorbing characteristics of the muffler to deteriorate.

[Means and Actions for Solving the Problems] An object of the present invention is to eliminate and solve the above-mentioned drawbacks of the prior art, and to provide a highly durable muffler described in the claims as means for achieving this object. Is what you do.

That is, the present invention is a sheet-shaped material having silica-alumina fiber having a fiber diameter of 1 to 3 μm and E glass fiber having a fiber diameter of 5 to 10 μm as main raw materials, formed into a predetermined shape using a binder, and An object of the present invention is to provide a highly durable sound-absorbing heat-insulating material which does not lose its sound-absorbing properties even when used for a long time in a portion where exhaust gas of not less than ° C passes.

By the way, the reason why the fiber diameter of the silica-alumina fiber is set to 2-3 μ is that it is generally available at low cost,
The maximum service temperature is 1260 ° C. as compared with glass wool, rock wool, asbestos and the like, so that the fiber is excellent in heat resistance. (Product name: Ibi wool bulk) Also, the fiber diameter of E glass fiber was set to 5 to 10μ,
An aggregate of fibers with a fiber shape larger than 10μ is inferior in durability because the entangled fibers collide with each other because they have strong rigidity and are easily broken.Fibers larger than 10μ are generally easy to stick to human skin Because it is bad. The reason why the fiber diameter is set to 5 μ or more is that fibers having a fiber shape smaller than 5 μ have a high bulk density when processed into a sheet shape and a reduced sound absorption coefficient. This is because the fiber has a fiber diameter of 5 μ or more.

In the present invention, the ratio of silica-alumina fiber and E glass fiber is 40-60% by weight of silica-alumina fiber,
The balance consists of E glass fiber, the total amount of which is 100% by weight.
The reason is that the ratio of silica-alumina fiber to E-glass fiber is excellent when the silica-alumina fiber is more than 60 wt%, but the heat resistance is excellent, but the fiber diameter is as small as about 2 to 3μ and the fiber length is too large for manufacturing. Exhaust gas flow rate of 10m / se due to unevenness and shortness
If it exceeds c, it will scatter.

If the silica / alumina fiber content is less than 40 wt%, it is durable against the exhaust gas flow rate, but if the exhaust gas temperature is higher than 600 ° C, the thermal deterioration of the E glass fiber will have a large effect, The E glass fiber breaks due to the vibration and is scattered.

Further, in the present invention, at least one selected from organic binders such as latex emulsions and inorganic binders such as silica sol is generally used in an amount of 10% by weight or less. If it is larger than the above, the volume occupied by the organic binder having a small apparent bulk density in the molded body increases, and the entanglement between the E glass fiber and the silica-alumina fiber decreases, which adversely affects the durability. Also, if the amount of the inorganic binder is more than 10% by weight, the binding between the fibers is too strong, and the durability against vibration and the like is significantly deteriorated.

 The present invention will be described with reference to examples.

[Example] 50% of silica 50% of alumina 50% of ceramic fiber bulk (trade name: ibiwool bulk) having an average fiber diameter of 2.3μ and E glass having an average fiber diameter of 7μ previously cut so that the fiber length becomes 70mm. 50% fibers make cotton was needle-punched current after the cotton mixing by a dry fiberizer, thickness 5 mm, the high durability acoustic insulation material molded into a sheet having a bulk density of 1.0 g / cm ^3, a solid content of 10% The diluted SBR-based latex was impregnated, wound around a pipe having an outer diameter of 100 mm without changing the bulk density, and then dried to form a 5 mm-thick cylindrical durable heat insulating material.

In addition, aperture ratio 30%, hole diameter 4mm, wall thickness 1mm, outer diameter 100mm
After fitting the cylindrical highly durable heat insulating material outside the cylindrical punching metal, and further fitting a metal pipe having a thickness of 1 mm and an outer diameter of 110 mm, the diameter of the center is 50 m at both ends of the cylindrical punching metal. Donut-shaped perforated metal (hole diameter 30%, hole diameter 4mm, wall thickness 1mm, outer diameter 100mm) with / m holes is welded all around.

Furthermore, on the outside of the donut-shaped punching metal, a 5 mm-thick highly durable sound-absorbing heat-insulating material formed into a sheet shape and punched with an inner diameter of 50 mm and an outer diameter of 110 m is attached. Apply a steel plate with a diameter of 110 mm, weld the front circumference to the end of the metal pipe,
A highly durable sound-absorbing heat insulator having a length of 110 mm and a total length of 200 mm, a pipe having a thickness of 1 mm, an outer diameter of 50 mm, and a length of 20 mm was inserted into openings at both ends, and a test piece shown in FIG.

A speaker having an outer diameter of 45 mm was placed on one side of the opening of the test piece, and "Rion Octave /
After measuring the sound absorption coefficient using the “Band Analyzer”, it was attached to the durability tester shown in FIG. 2, and the temperature was 800 ° C., the flow velocity was 25 m / sec, the frequency was 2930 cpm, the amplitude was 1.5 mm, and the vibration acceleration was 7
After a 720-hour test under the conditions of G, the sound absorption coefficient was measured again, and the results are shown in Table 1.

(Comparative Example 1) The results of a durability test performed in the same manner as in Example 1 without using any sound absorbing material are shown in Table 1.

((Comparative Example 2) 50% silica, 50% alumina, 80% ceramic fiber bulk with an average fiber diameter of 2.3μ and E with an average fiber diameter of 8μ
The results of a durability test performed in the same manner as in Example 1 using 20% of glass fibers are as shown in Table 1.

(Comparative Example 3) The same durability test as in Example 1 was performed using 20% ceramic fiber bulk consisting of 50% silica and 50% alumina and 2.3% average fiber and 80% E glass fiber having an average fiber diameter of 8μ. Is as shown in Table 1.

(Comparative Example 4) A durability test similar to that of Example 1 was performed using 50% of ceramic fiber bulk having 50% silica and 50% alumina and 50% ceramic fiber bulk having an average fiber diameter of 2.3μ and E glass fiber having an average fiber diameter of 20μ. The results are as shown in Table 1.

(Effects of the Invention) Compared with Comparative Examples 1, 3 and 4, the sound absorbing properties are excellent.

Compared to Comparative Examples 2, 3 and 4, the change over time in the sound absorption characteristics is small.

For the above-mentioned reason, in the exhaust pipe of the automobile, the muffler can be installed at a place where the exhaust temperature is higher than 500 ° C., and the high sound absorbing effect can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a model in which the highly durable sound-absorbing heat-insulating material of the present invention has a shape used in an actual pre-muffler. Second
The figure is a route diagram showing the durability test apparatus. DESCRIPTION OF SYMBOLS 1 ... Metal container, 2 ... Punched metal, 3 ... Highly durable sound absorbing heat insulating material, 4 ... Intake pipe, 5 ... Exhaust pipe, 11 ... Burner, 12 ... Heat exchanger, 13 ... … Solenoid valve, 14… Test piece, 15… Vibrator, 16… Frequency exchanger, 17… Pressure gauge, 18… Thermocouple, 19… Temperature indicator, 20… Temperature recorder, 21 …… Anemometer, 22… Vibration-proof rubber, 23 …… Regulator.

Claims (5)

(57) [Claims] 1. A silica-alumina fiber having an average fiber diameter of 1 to 3 .mu.m, a blended fiber made of E glass fiber having an average fiber diameter of 5 to 10 .mu. At least one selected from organic binders and inorganic binders such as silica sol
A highly durable sound-absorbing heat insulating material for an automotive engine pre-muffler, wherein the heat insulating material is formed into a predetermined shape using less than 10% by weight. 2. The method according to claim 1, wherein the silica-alumina fiber comprises alumina 45.
2. The durable sound absorbing and heat insulating material according to claim 1, wherein the balance is from 95 to 95% by weight of silica. 3. The highly durable sound-absorbing heat-insulating material is formed by cutting a nonwoven fabric made by an ordinary dry method by cutting or by a wet papermaking method.
Item 3. A highly durable sound-absorbing heat-insulating material according to item 2 or 3. 4. The exhaust system according to claim 1, wherein said pre-muffler is located at a portion connected to an exhaust pipe of an automobile and through which exhaust gas of 500 ° C. or more passes.
4. A highly durable sound absorbing and heat insulating material according to claim 3. 5. The mixed fiber of silica / alumina fiber and E glass fiber is characterized in that the silica / alumina fiber is 40 to 60% by weight, the balance is E glass fiber, and the total amount is 100% by weight. The highly durable sound absorbing and heat insulating material according to any one of claims 1 to 4, wherein